Sodium bis 2-ethylhexyl sulfosuccinate

Surfactants employed for w/o-ME formation, listed in Table 1, are more lipophilic than those employed in aqueous systems, e.g., for micelles or oil-in-water emulsions, having a hydrophilic-lipophilic balance (HLB) value of around 8-11 [4-40]. The most commonly employed surfactant for w/o-ME formation is Aerosol-OT, or AOT [sodium bis(2-ethylhexyl) sulfosuccinate], containing an anionic sulfonate headgroup and two hydrocarbon tails. Common cationic surfactants, such as cetyl trimethyl ammonium bromide (CTAB) and trioctylmethyl ammonium bromide (TOMAC), have also fulfilled this purpose however, cosurfactants (e.g., fatty alcohols, such as 1-butanol or 1-octanol) must be added for a monophasic w/o-ME (Winsor IV) system to occur. Nonionic and mixed ionic-nonionic surfactant systems have received a great deal of attention recently because they are more biocompatible and they promote less inactivation of biomolecules compared to ionic surfactants. Surfactants with two or more hydrophobic tail groups of different lengths frequently form w/o-MEs more readily than one-tailed surfactants without the requirement of cosurfactant, perhaps because of their wedge-shaped molecular structure [17,41]. 

Reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate in isooctane... 

The solubility of water is extremely low in hydrocarbons. For example, as low as 0.7% of water form the separate phase in decane (T = 298 K) [22], The surfactants create a small water micelle in hydrocarbon. For example, sodium bis-2-ethylhexyl sulfosuccinate (AOT) in the ratio H2O AOT = 20 creates stable micelles in decane with the diameter room temperature) [22]. The radii of a micelle r depends on the ratio H20 A0T the dependence has the following form [29] ... 

Recently, the phase equilibria of a microemulsion were reported. The phase behavior of a microemulsion formed with food-grade surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was studied. Critical microemulsion concentration (cpc) was deduced from the dependence of the pressure of cloud points on the concentration of... 

Aerosol OT (dioctylsulfosuccinate, sodium salt sodium bis(2-ethylhexyl)-sulfosuccinate) 444.6 2.5 a... 

Lang J, Jada A, Malliaris A (1988) Structiu-e and Dynamics of Water-in-OU Droplets Stabilized by Sodium Bis(2-Ethylhexyl) Sulfosuccinate. J Phys Chem 92 1946-1953... 

Reverse micelles are well known to be spherical water in oil droplets stabilized by a monolayer of surfactant. The phase diagram of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate, called Na(AOT), with water and isooctane shows a very large domain of water in oil droplets and often forms reverse micelles (3,23). The water pool diameter is related to the water content, w = [H20]/[ AOT], of the droplet by (23) D(nm) = 0.3w. From the existing domain of water in oil droplets in the phase diagram, the droplet diameters vary from 0.5 nm to 18 nm. Reverse micelles are dynamic (24-27) and attractive interactions between droplets take place. 

Aqueous pools of reversed micelles have been fruitfully employed for the in situ generation of semiconductor particles. The first publication in this area described the formation of CdS in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) aggregates in isooctane [611]. The preparation involved the addition of aqueous CdCl or Cd(N03)2 to isooctane solutions of AOT. Exposure to controlled ammeters of the CdS particles formed. Irradiation of degassed, AOT-reversed-micelle-entrapped, platinized CdS by visible light (450-W Xenon lamp X > 350 nm) in the presence of thiophenol (PhSH) resulted in sustained hydrogen formation. Sacrificial electron transfer occurred from thiophenol to positive holes in the colloidal CdS and, consequently, diminished undesirable electron-hole recombinations (Fig. 101) [611]. 

In the case of ionic surfactants, a reduction in aggregation number will result when the counter-ion radius is increased (Kon-no and Kitahara, 1971a). The change in the size of aggregates as a function of the structure of ionic surfactants was studied (Eicke, 1980 Kon-no and Kitahara, 1971a Kon-no et al., 1983 Matijevic, 1993 Ward and C. du Reau, 1993). The aggregation numbers of anionic surfactants (sodium bis(2-ethylhexyl)sulfosuccinate and sodium l,3-(2-... 

The polar group of surfactants is one of the essential factors determining the size of soft-core reverse micelles. In general, reverse micelles have moderate aggregation numbers carboxylates in toluene (5 to 20), calcium cetylphosphate plus calcium alkylphenolate in lube oil (20 to 30), tetra-n-alkyl-ammonium salts in benzene (3 to 25), and sodium bis(2-ethylhexyl)sulfosuccinate in dodecane (32), (Bascom et al., 1959). 

Soft-core reverse micelles are spherical or ellipsoidal aggregates consisting of a water core separated from a continuous apolar phase by a surfactant shell. It is well known that in the absence of water, some surfactants such as sodium bis(2-ethylhexyl) sulfosuccinate (AOT) can form dry aggregates, while others such as sodium dodecyl sulfate (SDS) or hexadecyl-trimethylamonium bromide (CTAB) need a cosurfactant, e.g., a short chain alcohol, to form micelles. 

Table 3.2. The physical properties of water in the water pool (WP) in reverse micelles of sodium bis-2-ethylhexyl sulfosuccinate (Aerosol OT or AOT) in isooctane. The spectroscopic properties of the hydrated electrons (e"aq) in the micellar water pool (Wo)...

Zhou N, Li Q, Wu J et al (2001) Spectroscopic characterization of solubilized water in reversed micelles and microemulsions sodium bis(2-ethylhexyl) sulfosuccinate and sodium bis(2-ethylhexyl) phosphate in n-heptane. Langmuir 17(15) 4505-4509... 

D Angelo, M., Fioretto, D., Onori, G., Palmieri, L., and Santucci, A. (1996), Dynamics of water-containing sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles A high-frequency dielectric study, Phys. Rev. E, 54(1), 993-996. 

Sim et al. reported the polycrystalline ceria NWs synthesized using sodium bis(2-ethylhexyl) sulfosuccinate as a structure-directing agent (Sun et al., 2004). The obtained Ce02 NWs were 30-120 nm in diameters and 0.2-5 pm in lengths, consisting of 7 nm sized nanocrystallites. 

SBO SOBITAL SODIUM BIS(2-ETHYLHEXYL) SULFOSUCCINATE SODIUM DI-(2-ETHYLHEXYL) SULFOSUCCINATE SODIUM DIOCTYL SULFOSUCCINATE SODIUM DIOCTYL SULPHOSUCCINATE... 

Finally, in the discussion of reverse microemulsion systems, mention should be made of one of the most widely studied systems. The surfactant, sodium bis(2-ethylhexyl) sulfosuccinate or Aerosol-OT (AOT), is one of the most thoroughly studied reverse micelleforming surfactants since it readily forms reverse micelle and microemulsion phases in a multitude of different solvents without the addition of cosurfactants or other solvent modifiers. The phase behavior of AOT in liquid alkane/water systems is already well documented. Indeed, the first report of the existence of the formation of microemulsions in a supercritical fluid involved an AOT/alkane/ water system. A The spherical structure of an AOT/nonpolar-fluid/ water microemulsion droplet is shown in Fig. 1. In the now well-known structure, it can be seen that the two hydrocarbon tails of each AOT molecule point outward into the nonpolar phase (e g., supercritical fluid). These tails are lipophilic and are solvated by the nonpolar continuous phase solvent whereas the hydrophilic head groups are always positioned in the aqueous core. 

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